How Much Acid Is Needed To Lower The pH In A Pool?

How Much Acid Is Needed To Lower The pH In A Pool?

Do you wish to lower the pH of your pool water? You are on the right page. First, you don’t need to pour any amount of acid into your pool – you would be doing more harm than good. But at the same time, it shouldn’t be left at a high pH. So, how much acid is needed to lower the pH level in the pool?

If your swimming pool has a pH reading between 7.8 and 8.0, and the volume is 20,000 gallons, you will need 0.25 gallons of muriatic acid. You can do a retest of water after it has circulated for an hour to determine whether the pH has been lowered to its ideal level.

If you have a swimming pool, it’s pertinent that you should manage the pH level very well. The good thing is that you don’t need to spend a fortune getting things right. You only need to know how to use the right acid to keep the pool pH balanced.

Muriatic acid is one acid you can add to your pool to lower the pH. It is pertinent to know more about how it works, how to rightly apply it, and what it entails. This piece is here to enlighten you on all that you need to know about this acid and more.

What is muriatic acid?

Muriatic acid which is also known as hydrochloric acid is used to care for the swimming pools. Because this acid is mildly corrosive it has been proven to be effective for pool maintenance. The essence of this acid is to help you reduce your pool water pH, whenever your pH level is elevated. You can get this acid at either a pool supply store or home improvement stores.

Why is muriatic acid better for lowering pool pH?

Though other acids like sulfuric acid can be used to lower the pH of a pool they are less commonly used because of their high concentration. Other acids are highly corrosive. And when they are added to the pool water, they are combined with the calcium in the water to wreak havoc on the pool surface. But muriatic acid is mild with about 31% corrosiveness. It works better in pools than other acids.

What causes the pH to be unbalanced in your pool?

Your pool pH wouldn’t just be unbalanced without factors instigating it. The following factors may be responsible for unbalanced pool water chemistry:

  • The source of water supply
  • The evaporation level in your pool
  • The water treatments you are using
  • The debris that drops into the pool
  • The different disinfectants you must have used to sanitize your pool
  • The swimmer’s waste deposited into your pool
  • The aeration of your pool

Reasons why you should apply muriatic acid to your pool

The whole essence of applying the acid to your pool is to help lower the pH of your pool. This will help to take away common problems that are associated with high pH level, which are:

  • Algae in the pool

Muriatic acid is great for removing very stubborn algae from both the walls and falls of a swimming pool. With its application, filtering out algae in the swimming pool becomes very effective

  • Metal corrosion or etching of the pool surface

It helps to lower the pool pH and prevent the damage high pH would have caused to the surface of the swimming pool which may lead to a high cost of replacement or maintenance of the pool.

  • Chlorine loss

This is another problem that comes with high pH. It renders the sanitizers that are used in the pool ineffective. So, lowering the pH will help to restore its efficiency.

  • Skin and eye irritation

The health of the swimmers wouldn’t be left out if the pool pH is high. It will make the skin dry and itchy. It irritates the eyes.

How much acid is needed to lower pH in a pool?

As we have already stated, one thing is knowing the acid to use for lowering your pool pH, but the most important is knowing the right quantities to use. Figuring this out will depend on two things. First, how high your pool’s pH is, and then, the size of your pool.

Just using a test strip may not always give the best estimate. It’s better to get a DPD drop test kit, and using phenol red is good too. But it will be a lot better if you can get an acid demand test kit. You can use it to calculate the right dosage as well. Depending on the capacity of your pool, you can use the below dosage;

If you have a reading of your pH at 7.8 or higher numbers and your pool water capacity is 20,000 gallons then you can use 0.25 gallon of the muriatic acid. If the pH reads between 8.0 and 8.4, the amount of acid should be 1.5 qts for 20,000 gallons of water. With the same pH level for 25,000 gallons, use 2 qts, and for 50,000 gallons of water you should use 1 gallon of the acid.

Now, if your pH is a lot higher than 8.4, you need to use more acid. 1 qts for 10,000 gallons of water, for 20,000 liters of water use 2qts, and 50,000 gallons of water use 5qts.

When you figure out the dosage, you need to know how to apply the acid properly. Below are the steps to take to get the application right:

  • Turn off the pump

Now, after getting the right quantity to apply to the pool, you need to shut down the pump. This is because when the pump is on it aids in the circulation of chemicals but still adds oxygen to it via bubbling and churning of the water. So this exposure to oxygen will in turn amplify the effects of the acid on the pH. If there’s a need to lower the pH of your pool, it is a lot better to minimize the water by turning off the pump. Other water features should be turned off as well.

  • Adding your acid to your pool to lower the pH

You can pour the right dosage of the acid into your pool but it will be a lot better if you dilute it. You know muriatic acid is corrosive, so diluting it will be safe and a lot easier to handle. It will be less harmful if it splashes on you. So, go ahead and dilute it first. Get a bucket, add water (the recommended ratio of water to your acid is 10:1) pour the right acid dosage into the water. Stir the solution with either a wooden or plastic stir stick.

Note that you should always add water to your bucket first before adding your acid. If you add your chemical first before adding your water, you would be running a risk of a huge chemical splash.

  • Apply the solution

Walk around the pool slowly and pour in the mixture as you move. This will help add air to the water and this will enable the chemical to circulate better as you apply. Once done, rinse the acid bucket thoroughly and make sure not to use it with other chemicals. You might just cause an explosive reaction.

  • Set it to work

Allow the pool for about an hour to make the solution circulate. Kicking the pump on to help the acid circulate faster wouldn’t be a bad idea. The essence is to help prevent the acid from settling on the bottom of the pool. This will help keep the acid from damaging the surfaces of the pool if it is just left to settle.

  • Retest your water

This is the last thing to do, you need to retest your pool pH to be sure it was lowered just the way you wanted it.

How to safely handle your acid?

Even though muriatic acid seems to be mild amongst other dry acids, it is still highly corrosive. It is just that it is the most suitable for the swimming pools. But it can still be harmful if not properly handled. When it comes to handling any chemical that has to do with your pool, you should always think of safety. A lot of them are incredibly corrosive and need not come in contact with your skin.

  • The first safety rule is to know when you are ready to add an acid. You need to add the acid when your pool pH has gotten higher than 7.8. So, avoid wrecking your pool by adding acid before testing your pool.
  • Try to keep the acid away from your skin. Avoid skin contact with the acid. The truth is that if the acid comes in contact with your skin, it will cause a burn that might require serious medical attention. So you need to be cautious.
  • Try to never allow contact with your eyes. It has the potential to cause permanent damage like blindness to the eyes. So handle with utmost care.
  • Do not inhale the fume of your acid; it can cause huge damage to your respiratory tract.
  • Make sure before you start handling the acid that you have your rubber gloves, boots, and safety goggles on.
  • Get all swimmers out of the pool before applying the acid.

What happens if you put too much acid in a pool?

The fact is if you add too much acid to your swimming pool, the pH level will dip very low. This may irritate the eyes and cause rashes. Also, to avoid damage to the pool metals like screws, railings, and bolts, you need to use the right dosage of the acid.

How long after adding acid to a pool can I swim?

After adding your acid you should wait 30 minutes before you can swim. Muriatic acid does create a hot acid in the water. So it can potentially burn or irritate the skin if you get in too quickly. This is why it is advisable to wait 30 minutes before diving. Remember, with a swimming pool you need to think about your safety first.

How often can you add muriatic acid to your pool?

It can be every 4 hours; if your pH level is still high then you can add more acid until you get the ideal pH for your pool. This should always be between the 7.2-7.8 optimum range.

Can I add muriatic acid and chlorine at the same time?

No, never you add chlorine and muriatic acid at the same time in your pool. This is because adding these two chemicals together will create a dangerous toxic gas. The effect will be severe health consequences if you inhale the fume.


Here you have all you needed to know about the doses of acid, you would need to lower your pool pH. The truth remains that leaving your pool at a high pH is damaging, not just to your pool but to your health as well. So you need to get the right chemical to help you lower it. But you are not done yet; you need to also know the quantity that will give you the optimum level for your pool.

That is what this piece is all about. By the time you are done reading this post, you should have been able to figure out the right quantity of acid you need for your pool. The bottom line is that you should get your acid and know the quantity to use. But importantly, don’t forget to always protect your skin when at it.

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